Reversible engine control apparatus



April 21, 1953 R. BROOKS 2,635,417

REVERSIBLE ENGINE CONTROL APPARATUS Pave rse Conrrol Pipe Filed 001,. 7. 1949 5 lvaika a 11 y Kg 5| 4 5 Sin? Full Fuel P 55 6 34 E7 12 9/ 55\ Fuel Off V 4/57 2 L V Z? G 6 4 74* 62 g 55 75 Engine Fuel Confrol Shaf'f .22.. 1/ 65 60 615 68 5'6 64 INVENTOR.

Ra lph GBrooKa BY I ATTORNEY Patented Apr. 21, 1953 REVERSIBLE ENGINE CONTROL APPARATUS Ralph 0. Brooks, Turtle Creek, Pa., assignor to Westinghouse Air Brake Company, a corporation of Pennsylvania Application October 7, 1949, Serial No. 120,121

9 Claims.

This invention relates to reversible engine control equipment and more particularly to control apparatus adjustable in accordance with the direction of rotation of a reversible engine for controlling the supply of fuel to same.

In certain fluid pressure reversible engine control systems, a directional interlock valve device is employed in reversing the engine to effect holding of the fuel supply to the engine cut-off until the engine is rotating in its proper direction in accord with the position of an operators control lever. Such an interlock device usually comprises a retractable shoe which is adapted to be actuated into frictional engagement with a rotary part of the engine, such as the crank shaft, to be biased in one or another direction according to rotation of the crank shaft for conditioning a fuel control device accordingly.

Heretofore, in the control systems employing the above directional interlock valve device, if, in reversing the engine, the operator moved the operators control lever to a position to call for termination of the supply of starting air and for the supply of fuel to the engine at a time when the engine crank shaft has merely begun to turn in its new or reverse direction: such termination would be effected, the directional interlock device would assume its reverse position for allowing fuel to be supplied to the engine while the shoe of the interlock device would move to its retracted position away from the engine crank shaft. Under these conditions, if the engine rocked so that its crank shaft momentarily started to turn back in its original direction of rotation there was danger that the fuel supplied to the engine might fire and cause unintended running of the engine in its original direction of operation, and with the directional interlock shoe retracted, the directional interlock device would be helpless to prevent such unintended running, so that damage to the engine and equipment might result before the operator could cut off the fuel supply through manipulation of the operators lever.

It is a principal object of the present invention to provide reversible engine control apparatus comprising a directional interlock device which will operate automatically to prevent the above described unintended running of the engine should rock occur during engine reversal.

Other objects and advantages will become apparent from the following detailed description of the invention.

In the accompanying drawing, the single figure is a schematic view of a control system embodying the invention.

Description The reversible engine (not shown) may comprise the usual crank shaft I, only a portion of which is shown in the drawing. The crank shaft 1 may be operably connected to the pistons (not shown) of the engine and operatively connected to a device to be operated (not shown). The

engine may further comprise a fuel control shaft 3 operatively connected to fuel control valve means (not shown) for regulating the quantity of fuel supply to the engine by way of fuel injection nozzles or the like (not shown). The control shaft 3 is secured for turning movement with a fuel control lever 4 which may be disposed outside the engine. The lever 4 is arranged to be moved to a Fuel Off position, indicatedby a dot and dash line'so legended in the drawing, in which position the fuel control valve means is conditioned to shut off the supply of fuel to the engine cylinders. By a counterclockwise turning movement of lever l, as viewed in the drawing, from its Fuel Off to a Full Fuel position, the fuel may be increased up to a maximum amount corresponding to the latter position. The fuel control lever 4, when not otherwise urged to its Fuel Oil position and when the engine is turning over will be caused to assume positions out of Fuel Oil toward Full Fuel according to dictates of such as a speed governor device (not shown).

The control apparatus embodying the invention may comprise a starting air control valve device 6, a fuel cut-off cylinder device 5 for effecting movement of the fuel control lever 4 to its Fuel Off position, as in stopping the engine for reversal, a directional interlock device I for controlling operation of the fuel cut-off cylinder device 5, an operators control device 8 for controlling the operation of the directional interlock device 1, and, according to the invention, a choke 9 and check valve Ill interposed between the operators control valve device 8 and the directional interlock valve device 7.

In addition, the control apparatus comprises a fluid pressure reservoir H adapted to receive fluid under pressure from such as a compressor (not shown) as a source of supply of working medium for the control system as well as a source of supply of starting air for the engine. A reducing valve 12 is provided to transform reservoir pressure to a pressure suitable for operation of the control system.

The fuel cut-off cylinder device 5, for sake of illustration, may comprise a hollow cylindrical casing 36 having a fuel cut-off piston 3| slidably disposed therein. Piston 3! is arranged to be exposed on its one face to pressure of fluid in a pressure chamber 32 and on its opposite face to the force of a compression spring 33 disposed in an atmospheric chamber 35. A stop rod 35, attached to piston 35, extends outwardly through th casing 30 for engagement with the fuel control lever 3. When fluid under pressure is supplied to the pressure chamber 32, the piston 3| will be caused to assume the position in which it is shown in the drawing, with the stop rod 35 in engagement with the fuel control lever t and holding same in its Fuel Off position. Upon release of fluid under pressure from the pressure chamber 32, the piston 3I will be moved by spring 33 in the direction of chamber 32 to a release position defined by contact with a shoulder 36, in which position the stop rod 35 will be retracted away from the fuel control lever 4 to allow same to be moved in the direction of a Full Fuel position by means of a speed governor device (not shown) or the like for effecting the supply of fuel to the engine.

The starting air valve device 6 may comprise a casing 53 having a diaphragm 54 disposed therein and subject to the pressure of fluid in a diaphragm control chamber 55 on one side and to the pressure of fluid in a chamber 56 on its opposite side, which latter chamber is open to atmosphere via a port 51 in the casing. Also formed in the casing are chambers 58, 59 and 60, chamber 58 being separated from chamber 56 by a partition 6I and from chamber 59 by a partition 62. A partition 63 separates chambers 59, 60. A valve 64 is disposed in chamber 60 for controlling communication between said chamber and the chamber 59. Valve 64 may be secured to a fluted stem 65 slidably mounted in a suitable bore extending through the partition 63, a seat being formed at the end of said bore to accommodate said valve. A bias spring 68 is disposed in chamber 60, arranged to urge the valve 64 in the direction of its seat. A valv 69, similar to valve 64, is disposed in chamber 58 for controlling communication between said chamber 58 and the chamber 59. For slidably guiding the valve 69, a fluted stem 10 is provided which is slidably disposed in a suitable bore opening through partition 62. A valve seat i formed in partition 62 encircling one end of the last mentioned bore for accommodating the valve 69. Stems 65, 10 project into and meet in the chamber 59 in such a manner that action of bias spring 68 on valve 64, in urging same in the direction of its seat, at the same time, through said stems, urges valve 69 in a direction away from its respective seat. If valve 69 is seated, valve 64, con sequently, will be unseated. Valve 69 is operably connected to the diaphragm 54 by means of a rod or stem 13 extending therebetween through a bore in partition 6I in which said rod is slidably disposed. A control spring 16 is provided in chamber 56, arranged to oppose deflection of the diaphragm 54 in the direction of chamber 56 as caused by pressure of fluid in chamber 55 for determining the degree of said pressure necessary to effect operation of valves 64, 69.

In operation, the device 6 will respond to a certain pressure of fluid in the control chamber 55 to close valve 69 and open valve 64 thereby closing chamber 59 to chamber 58, while at the same time opening said chamber 59 to the chamber 60. Upon a subsequent certain reduction in pressure of fluid in control chamber 55, springs 68 and 16 will close valve 64 and open valve 69 to again connect chamber 59 to chamber 58 and to close said chamber 59 from chamber 60.

In the starting air valve device 6, the chamber 59 is connected to a pipe for conveying start ing air to the engine, chamber 60 is connected to the reservoir II by a pipe 14, and chamber 58 is open to atmosphere via a port 80.

The directional interlock device 1 in the usual form comprises a casing having two poppet valves I3I and I32 contained in chambers I33 and I34 respectively. The poppet valves I3I and I32 are arranged side by side with parallel extending fluted stems I35 and I36, respectively, which extend into a chamber I31 common to both. The valves I3I and I32 are provided to control communication between the chambers I33 and I34, respectively, and chamber I31. A spring I38 in each of the chambers I33 and I34 acts on th rcspective valve I3I, I32 to urge same toward a closed position, in which position the valve I3I is shown in the drawing.

The valve stems I35 and I36 engage, respectively, two spaced apart operating plungers I39 and I40 which are slidably mounted in the casing and which are provided with stems MI and I 42 extending outwardly through the casing. Two rockable cams I44 and I45, fulcrumed on pins secured to the casing, are provided for actuating the plungers MI and I42, respectively. These cams may be identical but reversely arranged, and each is operatively connected to the respective plunger I4I, I42 through the medium of a follower element I41 rockably mounted on a pin secured in the casing. Each of the cams I44 and I45 is provided with a surface I49, which, when in engagement with the respective element I41, will unseat the respective valve I6I or I32. Adjacent to the surface I49, each cam is provided with a recess I50 which is adapted to receive the respective element I41 to permit movement of the respective plunger I39 or I40 by a spring I5! to a position to permit closure of the respective valve I3I or I32 by the respective spring I36.

The two cams I44 and I45 are operatively connected for movement in unison by a link I52. and since the cams are reversed as above mentioned, movement of the link and cams to the position in which they are shown in the drawing will effect opening of the valve I32 and closure of the valve I3I, while movement of said link and cams in an opposite direction to a position in which the surface I49 on the cam I44 engages the respective element I41 will effect opening of the valve I3I and closing of the valve I32.

The directional interlock device 1 further comprises a shoe actuating piston I54 which is operatively connected to the link I52 by means of a piston rod I55, which extends through a nonpressure chamber I56 at one side of said piston. At the opposite side of the piston I54 there is a pressure chamber I51. The opposite or outer end of the piston rod I55 is connected by a pin I59 with a friction shoe I6I which is adapted and arranged for frictional engagement with the outer surface of the crank shaft I. The piston rod I55 is also operatively connected by means of pin I59 to one end of a link I63, the opposite end of which is operatively connected to the link I52 by means of a pin I63.

The piston rod I55 is capable of side movement in the non-pressure chamber I56 from the position in which it is shown in the drawing, and which is defined by contact with a surface I64 in the casing, to a position in which said rod engages a surface I 65 in the casing. Adjacent to the surface I65, the casing is provided with a pin I66 which is arranged to engage in one of two recesses I61, I68 according to whether or not the piston rod is in the position in which it is shown in the drawing or is in its opposite position engaging the surface I65.

When fluid under pressure is supplied to the pressure chamber I51, in a manner which will be described hereinafter the piston I54 will move the friction shoe I6I into engagement with the engine crank shaft I, which, if rotating, will bias the rod I55 toward one or the other of surfaces I64 or I65, according to the direction in which said shaft is turning. At the time of engagement of the shoe ISI with the shaft I, the link I53 will be disposed away from the pin I56, so that the rod I55 is free for sidewise movement to effect positioning of the cams I04 and I45 accordingly. If, at the time of engagement of the shoe It! with the shaft I, said shaft is rotating in one or its Forward direction, the rod I55 will be biased to the position in which it is shown in the drawing in leaning engagement with the surface I66, and the cams I42 and I25 therefore Will be caused to assume the positions in which they also are shown in the drawing with the valve I 3i consequently closed and the valve I32 open. If, conversely, the shaft I is rotating in the other or its Reverse direction at the time of engagement by the shoe IISI, the rod I55 will be caused to assume its opposite position in leaning engagement with the surface I65, thereby effecting shift of the cams I44, I45 to their positions in which the valve I32 is closed and the valve I3I is opened. If, however, at the time that the shoe IB-I engages the shaft I, said shaft is static, the rod I55 will remain in leaning engagement with Whichever of the shoulders I64 or I65 it may be in such engagement with at the time. Upon release of fluid under pressure from the chamber I57, a spring I'IG will move same in the direction of said chamber to a rest position in which it is shown in the drawing, While the shoe IISI will thereby be moved to a corresponding rest position seated on accommodating shoulders I'Il formed in the casing. The link I53 will return into contact with the pin I55 which will project into one or the other of the recesses I61 or I68 to lock the piston rod 555, cams I4, I45 and the valves IBI, I32 in the positions which they were caused to assume when the shoe I6I last engaged the shaft I when rotating.

In the directional interlock device I the chamber I3! is connected via a pipe I80, a shuttle valve IBI and a pipe I 82 to the chamber 52 in the fuel cut-off cylinder device 5, the chamber I34 is connected to a Reverse Control Pipe I85, the chamber I33 is connected to a Forward Control Pipe I86, and according to the invention, the chamber I? is connected to the outlet side of the choke 9 and check valve I0 by way of a pipe Itll and a branch thereof. The inlet sides of the choke Ii and check valve IE are connected to branches of a Start Control Pipe v202 which has a connection with the chamber 55 in the starting air valve device 6.

The operators control device 8 may be of the type described in United States Patent No. 2,433,916 issued to H. C. May et al., January 6, 1948, and briefly may comprise an operators control lever 200 adapted to be moved to various positions within a guide slot 20I for actuating valve means (not shown) comprised therein for selectively establishing pressurization of the Forward Control Pipe I36, Reverse Control Pipe I85, and a Start Control Pipe 202, as Well as to effect variation of pressure of fluid in a speed control pipe 203.

In the usual control system, variation in pressure in the speed control pipe 203 is employed to effect a corresponding regulation in the speed setting of the governor device, however, such regulation is not pertinent to the present invention, and description of such variation as effected by the operators control device 8 has been omitted from the present application.

In operation of the operators control device 8,

only establishment'of supply and release of fluid under pressure .to and'from the control pipes I85, I86, 202 will be considered herein, since only those are pertinent to an understanding of the invention.

When operators lever 200 is :moved to Stop position, in which position it is shown in the drawing, the control pipes I85, I86 and 202 are vented to atmosphere.

When the operators lever 200 is moved out of Stop position in the slot 20I in the direction tilted Forward, the Forward Control Pipe I86 will be charged with fluid under pressure, while the Reverse Control Pipe I 35 and the Start Control Pipe 202 remain vented.

When the operators lever 200 is moved in slot 201 out of Stop position .in'the opposite direction, that is, in the direction bearing the legend Reverse, the Reverse Control Pipe I85 will be charged with fluid under pressure while the Forward Control Pipe I86 remains vented as in Stop position.

By movement of operators lever 20!] from slot 20I on either the Forward or Reverse sides of Stop position into and out of respective slots 2E0, 2II to respective Start positions, the Start Control Pipe 202 will be charged with fluid under pressure and vented, respectively, while the status of the control :pipes I86, I85 will remain unaffected by such movement into and out of the Start positions.

In the usual manner, with the operators control lever 2% in Stop position and the control pipes I85, I86 and 22.2 vented, the chamber 32 in the fuel cut-01f cylinder device 5 will be charged with fluid under pressure supplied thereto by Way of pipe I32, shuttle valve I BI and a pipe at which in turn is usually supplied with fluid under pressure by way of a relay valve device (not shown) which responds to enting of both control pipes I85, I36 to effect such supply to the pipe a:. When the operators lever 200 is moved out of Stop position in either direction, with one or the other of pipes I85, I86 consequently charged with fluid under pressure, the relay valve device (which is not shown) will vent the pipe 3:. It will therefore be seen that control of operation, that is, supply and release of fluid under pressure to and from the .fuel cut-off cylinder device 5, will be under the control of the directional interlock device 7, via pipe I80, shuttle valve Iti, and the pipe I82 when the operators control lever 20%) is out of Stop position, as will be true when reversing the engine, for example.

Operation Assume that the operators control lever 200 is positioned in slot 2f at the Forward side of Stop position intermediate Full Speed and Run. and Idle, for example, with the Forward Control Pipes I85 consequently charged with fluid under pressure and the Reverse Control Pipe and Start Control Pipe vented; assume that the engine is running with crank shaft I turning in its Forward direction; and assume that the directional interlock device "I is in its corresponding forward position .in which it is shown in the drawing with valve I32 unseated, opening pipe 83 to Reverse Control Pipe I85, and with the valve IS'I seated, closing off the pipe I from the Forward Control Pipe I06.

With the Reverse Control Pipe I vented, the chamber 32 in the fuel cut-01f cylinder device 5 also will be vented via pipe I82, shuttle valve I8I, pipe I80, the unseated valve I32 in the directional interlock device 1, and said "Reverse Control Pipe so that piston 3| in said device 5 will be so positioned that stop rod 35 will be in its retracted position disposed away from the fuel control lever 4, allowin for supply of fuel to the engine assumed to be running forward.

With the "Start Control Pipe 202 vented, the chamber I51 in the directional interlock valve device 1 will be vented by way of the pipe I90, choke 9, and said Start Control Pipe as also will be the chamber 55 in the starting air valve device.

With chamber I 51 vented, the piston I54 in the directional interlock valve device 1 will be in the position in which it is shown in the drawing with the shoe I6I in its retracted position disposed away from the crank shaft I assumed to be turning in its Forward direction.

With chamber 55 in the starting air valve device 6 vented, it will be appreciated from previous description of operation of said device 6 that starting air supply to the engine Will be cut oil by the sea ted valve 64 while the engine starting air pipe 15 will he vented via the unseated valve 69.

Now assume that the operators lever 200 is moved from its position in slot 20I on the Forwe rd side of Stop position to Start position in slot 2II on the Reverse side of Stop position, so that consequently the Forward Control Pipe I85 will become vented, while the Reverse Control Pipe" and Start Control. Pipes 85 and 202 become charged with fluid under pressure.

In response to such change in pressure status in the control pipes I85, I88, engine reversing mechanism (not shown) will effect conditioning of the engine for operation in its reverse direction.

In response to supply of fluid under pressure to the Reverse Control Pipe I85, fluid under pressure will flow therefrom by way of the unseated valve I32 in the directional interlock device 1, the pipe I80, shuttle valve I8I and pipe I82 to the chamber 32 to cause movement of stop rod 35 and thereby movement of the fuel control lever 4 to its Fuel Off position to terminate supply of fuel to the engine.

Fluid under pressure supplied to the Start Control Pipe 202 will flow to chamber 55 in the starting air valve device 8 to cause starting air to be supplied to the engine and, by way of the check valve I and pipe I90, such fluid under pressure also will flow to the chamber I51 in the directional interlock device 1 to cause the shoe IIiI to be moved into frictional engagement with the rotating crank shaft I.

Supply of starting air to the engine at this time will act to slow down the engine rotating in its original Forward direction until same stops and under normal conditions will then turn the engine over in its new or Reverse direction if such supply of starting air is maintained.

As soon as the engine crank shaft I starts to turn over in its new or Reverse direction, by sidewise movement of the shoe I6I with the shaft I, the directional interlock device I will assume its reverse position seating valve I32 and unseating valve I3I, for thereby releasing fluid under pressure from chamber 32 in the fuel cutoff cylinder device by way of the unseated valve I 3| and the Forward Control Pipe I86 and allowing the fuel control lever 4 to move to a fuel supply position. The engine will then run on fuel in its reverse direction and the interlock shoe IGI then may be retracted through release of fluid under pressure from chamber I51 and termination of supply of starting air effected. through release of fluid under pressure from chamber 55 in the starting air control valve device 6. Such release of fluid under pressure will be effected through venting of the start control pipe 202 by movement of operators lever 200 out of Start position into slot 20I.

According to the invention, should the start control pipe 202 by prematurely vented to cause termination of starting air supply by movement of operators lever 200 out of Start position into slot 20I, that is, vented at a time when the engine has just begun a portion of a revolution in its new or Reverse direction sufficient to cause the directional interlock device to assume its reverse position in which fuel cut-off cylinder device chamber 32 is vented via unseated valve I3I the choke 9 will act to so restrict release of fluid under pressure from the chamber I51 in the directional interlock valve device 1 as to maintain the shoe I6I in engagement with the crank shaft I for sufiicient time as will assure that said interlock device will respond to any rocking of the engine back in its original direction to again assume its forward position and effect, through unseating valve I32, resupply of fluid under pressure to the chamber 32 in the fuel cut-off cylinder device 5 to move the fuel control lever 4 to its Fuel Off position. It will be seen that under such an operating condition as assumed above, by delaying retraction of the directional interlock shoe I6I away from the shaft I, the fuel supply to the engine is cut off automatically in case of engine rocking, so that in reversing the engine it is not possible for the engine to start to run on fuel in the wrong or original direction so long as the operators lever 200 remains in its position to call for reversal of the engine.

With the operators lever 200 in slot 20l on the forward side of Stop position and the Start Control Pipe 202 therefore vented, fluid under pressure will continue to release from the chamber I51 in the directional interlock valve device 1 and the shoe I6I will move to its retracted position while said interlock valve device remains in its forward position to hold fuel supply cut off.

To continue starting of the engine in its new or Reverse direction, the operator will move the operators lever 200 back into slot 2 II to Start position to again cause fluid under pressure to be supplied to the start control pipe 202, whereupon the directional interlock device chamber I51 will again be rapidly charged with fluid under pressure by way of check valve I0 to cause engagement of shoe I6I with shaft I while fluid under pressure will also flow to the chamber 55 in the starting air valve device 6 to cause starting air to be supplied to the engine to turn same over in its reverse direction.

The directional interlock valve device 1 will then respond to shift from its forward to its reverse position to release fluid under pressure from the fuel cut-off cylinder device chamber 32 to allow fuel to be supplied to the engine for running same in its reverse direction.

Termination of supply of starting air and retraction of interlock shoe IGI may then be effected in manner as aforedescribed by movement of operators lever 200 out of Reverse Start" position back into slot 20I.

It will be appreciated that direction of operat1on of the engine may be reversed in the opposite direction, that is, from Reverse to Forward, in substantially the same manner as above described, by movement of the operators lever 260 from its position in slot 26! on the Reverse side of Stop position to the Forward Start position. It will be seen too, that according to the invention, the choke 9 will function to delay retraction of the interlock shoe it! to prevent unintentional running of the enine backwards should the operator move the lever 260 from Start position back into the slot 20! cutting off supply of starting air prematurely at a time when engine rocking might occur.

Having now described the invention what I claim as new and desire to secure by Letters Patent, is:

1. In combination with a reversible engine crank shaft rotatable in either of two opposite directions, a fluid pressure conduit, a fluid pressure chamber connected to one end of said conduit, interlock means rendered sensitive to direction of rotation of said crank shaft, upon supply of fluid under pressure to said chamber, to assume a position corresponding to such direction and rendered insensitive upon release of fluid under pressure from said chamber while maintaining such position, choke means in said communication to restrict release of fluid under pressure from said chamber, and check valve means in said communication to allow for facile flow of fluid under pressure to said chamber.

2. The combination as set forth in claim 1, including engine reversing control means having two positions corresponding to the two directions of rotation of said crank shaft and operable while in said positions to effect supply and release of fluid under pressure to and from the opposite end of said conduit.

3. The combination as set forth in claim 2, including engine fuel cut-off means operable to cut off supply of fuel to said engine when position of said interlock means is not in accord with position of said reversing control means.

4. The combination as set forth in claim 3, including engine starting means operable upon supply of fluid under pressure to said opposite end of said conduit to urge the engine to turn over in a direction in accord with position of said engine reversing control means and to terminate said urge upon release of fluid under pressure from said opposite end of said conduit.

5. In combination with a reversible engine crank shaft rotatable in either a forward direction or in a reverse direction, a source of fluid under pressure, a start control pipe, a forward control pipe, a reverse control pipe, a delivery chamber, operators control means operable to forward positions to effect supply and release of fluid under pressure to and from said start control pipe while maintaining said forward control pipe charged with fluid under pressure and said reverse control pipe vented and operable to reverse positions to effect supply and release of fluid under pressure to and from said start control pipe while maintaining said reverse control pipe charged with fluid under pressure and said forward control pipe vented, valve means movable to a forward position or to a reverse position to establish connection between said dolivery chamber and said reverse control pipe or said forward control pipe, respectively, direction sensing means movable by engagement with said shaft when rotating in its forward direction to effect movement of said valve means to its said forward position and when rotating in its reverse direction to effect movement of said valve means to its said reverse position, a fluid pressure chamber, actuating means responsive to supply and release of fluid under pressure to and from said fluid pressure chamber to effect movement of said direction sensing means into and out of engagement with said shaft, respectively, and choke and check valve means connecting said fluid pressure chamber to said start control pipe for restricting release of fluid under pressure from said fluid pressure chamber and allowing facile flow of fluid under pressure to said fluid pressure chamber.

6. The combination as set forth in claim 5, including engine fuel cut-off means responsive to supply of fluid under pressure to said delivery chamber to effect cut-off of fuel supply to said engine.

'7. The combination as set forth in claim 6, including starting air control means responsive to supply of fluid under pressure to said start control pipe to effect supply of starting air to said engine and responsive to release of fluid under pressure from said start control pipe to terminate said supply of starting air.

8. In combination with a directional interlock valve device comprising a fluid pressure chamber and motion sensing means movable into and out of a motion sensing position in response to supply and release of fluid under pressure to and from said fluid pressure chamber, respectively, choke means for restricting release of fluid under pressure from said chamber, and check valve means arranged in by-passing relation to said choke means to allow for facile flow of fluid under pressure to said chamber.

9. Apparatus for controlling supply of fuel to a reversible internal combustion engine having a crankshaft subject to a momentary rocking condition at time of engine reversal, said apparatus comprising fuel control means renderable sensitive to direction of turning movement of said crankshaft to effect supply and cut-off of supply of fuel to said engine according to whether or not said crankshaft is turning in a forward or a reverse direction, respectively, and renderable insensitive to direction of turning movement of said crankshaft to allow fuel to remain in supply or cut-off to said engine according to whichever condition is established at the time said fuel control means is rendered insensitive, operators control means operable selectively to render said fuel control means either sensitive or insensitive, timing means interposed between said fuel control means and said operators control means to delay response of said fuel control means to operation of said operators control means to render said fuel control means insensitive, to allow said fuel control means to remain sensitive for a period of time greater than the time in which said crankshaft rocking condition will exist, and means rendering said timing means ineffective when said fuel control means is being rendered sensitive.

RALPH C. BROOKS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,413,390 Stevens Dec. 31, 1946 2,438,427 Whitney Mar. 23, 1948 2,515,970 Stevens et al July 18, 1950 2,540,765 Stevens Feb. 6, 1951 

